Core cap



Dec. 7, 1943. J BLANCHET 2,336,161

'CORE GAP Filed NOV. 25, 1941 FIG. I.

' JOSEPH EA. BLANCI'IET Imventor Mai/J4 f.

(lttorneg Patented Dec. 7, 1943 CORE CAP Joseph E. A. Blanchet, Mystic, Conn., assignor to Sonoco Products Company, a corporation of South Carolina Application November 25, 1941, Serial No. 420,397

2 Claims.

My invention relates towinding cores for paper or other web material and more particularly to an improved core cap for use on such cores. Metal caps are commonly used on the ends of paper tubes whichserve as cores for heavy rolls of paper. These caps provide means for connecting the core with a driving mechanism to effect winding or unwinding of the web material. Also, they protect the ends of the paper tube cores against the wear and strain encountered during the winding and unwinding operations and handling oftheheavy paper rolls.

One of the commercial problems which has existed in connection with these metal core caps is that of constructing the cap so that it will withstand the turning stress encountered in the winding operations and will stay in fixed position on the end of the paper tube; that is, notpermit rotative or endwise movement between the cap and tube.

Some of the prior forms of cores employ single walled plugs, instead of caps, with annular end faces which only abut the ends of the paper tube when the plug is inserted therein. This type of construction is subject to the objection of not sufficiently engaging the end of the tube to maintain a fixed position when stresses or turning moments are applied. A known form of metal, core cap is of spaced Wall construction, which oiiers better support for the paper tube than the plug type. Nevertheless, it is so constructed that it does not adequately resist rotative and endwise movement between the cap and core during the Winding and unwinding operation when power a is applied at the end of the core.

In accordance with my inventionl have overcome these practical problems and have developed acore .cap which meets the necessary commercial requirements. One of the principal features of my cap is the provision .of longitudinal spaced ribs disposed around the periphery of the inner wall of the cap which function to ribute the stresses, provide a substantially tighter fit between the cap and the paper tube and markedly increase the resistance to relative movements between the cap and tube.

The details of construction and mode of use of the core cap of my invention will be more fully understood from the following description taken in conjunction with the accompanying drawing in which:

Fig. 1 is an isometric View of the core cap;

Fig. 2 is an end view thereof;

Fig. 3 is a side view, partly in section;

Fig. 4 is a longitudinal sectional view of the core cap mounted on a paper core; and,

Fig. 5 is an enlarged detail.

The specific but non-limiting embodiment of the core cap shown in the drawing is made of a single piece of sheet metal which is formed into an inner cylinder it and a spaced outer cylindrical sleeve or end H. is substantially shorter than the cylinder ill but has an appreciably greater diameter so that an annular space i2 exists between these two cylinders for reception of the paper tube. The two cylinders It and H constitute ineffect the inner and outer walls, respectively, of the core cap and are integrally connected by the flattened rim portion IS.

A notch or recess shown at M is formed in the cylinders It and H to provide a keyway for the driving stud or key of the winding mechanism (not shown) which effects rotation of the roll for the winding and unwinding operations. The driving connection made through the notch M ncrmally creates a substantial strain on the core cap at this point and often fractures or distorts the adjacent metal surfaces. Accordingly, it has been common practice to employ a reinforcing metal insert around the notch.

Furthermore, the fact that the driving power (used for winding) is concentrated around the notch area, places a strain on the connection between the core and end cap of such magnitude that slipping or relative rotative movement between the cap and core often results. This causes inefficient winding as the slipping becomes progressively Worse and finally the cap rotates on the core and winding of the web on the core stops.

The improvements made in my core cap by proper utilization of the force distributing ribs completely avoid the necessity of any notch reinforcements and even more important prevents slipping of the cap on the cor in the usual winding or unwinding operations, as will appear from the following description.

The inner wall or cylinder iii of my core cap has formed therein a number of ribs l5. It will be noted that these ribs are uniformly spaced around the cylinder iii and are formed by pressing out portions of the sheet metal along substantially straight lines parallel to the longitudinal axis of the end cap. These ribs extend substantially the full length of the inner cylinder Ill and in the embodiment shown have similar size spaces between adjacent ribs around the periph cry of the inner cylinder. This represents a con- The cylindrical cuff ll struction which I have tested and found commercially advantageous but it is to be understood that the number, spacing and length of these ribs may be varied appreciably within the purview of my invention.

One apparent function of these ribs is to distribute the strains and stresses, applied to the core cap, substantially uniformly throughout the entire cap and end of the paper tube and avoid a concentration of stresses around the notch M or at any other point or small area. of these ribs is to divide the core cap into a number of sections each of which carries a similar small portion of the load or stress and thereby assures uniform distribution of the applied forces.

The effective coaction of the ribs l and paper tube l! for preventing slipping of the core can on the tube is illustrated in Figs. 4 and 5. When the core cap is driven onto the end of the tube I! the ribs l5 cause the paper to be tightly compressed around each rib and thereby crowds a relatively large amount of paper into the space between the ridge or upper surface of the rib and the opposite surface of the enclosing cuff I I. This provides a very tight fit between the end of the paper tube and the opposing walls of the inner sleeve I!) and the outer sleeve or cuff l l.

The somewhat vertically extending side portions of the ribs, shown in Fig. 5, serve as stops or abutment for the contiguous compressed areas of the paper tube and substantially prevent rotative movement therebetween. The complementary formation of these ribs are the grooves or indentations formed on the inner surface of the cylinder Ill and shown in the drawing by the reference numeral l6. They indicat the portion of metal which has been pressed out to form the ribs.

For purposes of determining the improvement and advantages of my core cap over the prior types of core caps which do not have the ribs, I have made actual comparable tests With the following results:

Standard core cap My improved core cap Moved 200 lbs. Broke 300 lbs.

Moved 290 lbs. Did not break 520 lbs.

These tests were made by holding the paper tube fast and applying a rotative force to the metal end cap as would occur in actual winding operations. The force necessary to cause relative movement between the core cap and the paper tube or core was measured in pounds as shown above. The values obtained under comparable conditions clearly show the superiority of my core cap as compared with a well known commercially used core cap. Because of the distribution of the applied force by the ribs used in my core cap the connection between the cap and core could not be broken even at the relatively very high force of 520 pounds.

While I have described the core caps as being made of metal, it is to be understood that any other suitable material, such as wood or hardened plastic having the necessary strength characteris- The effect tics, may be used. Likewise, various other modifications and changes may be made in the core cap as above described without departing from the scope of my invention, some of the novel features of which are defined in the appended claims.

I claim:

1. A rigid core cap for attachment to the end portion of a paper tube and so constructed that endwise connection therebetween will not break down under rotative stresses of as great as 500 pounds, said cap comprising an inner cylindrical sleeve adapted to be inserted into the end of the paper tube, and an outer cylindrical sleeve of shorter length but larger diameter integrally connected to said inner sleeve and circumferentially spaced therearound so as to provide an annular space for receiving the end portion of the paper tube with a tight fit, said inner sleeve having a plurality of external, longitudinal, ribs of blunt, non-cutting edge formation extending substantially the full length of the inner sleeve including the portion lying within said tube-receiving annular space, said ribs so limiting the space between them and the inner surface of the outer sleeve that the end portion of the paper tube is greatly compressed therebetween and thereby caused to assume an extremely tight fit that is strongly resistant to rotative displacement, and the blunt formation of said ribs causing indentation of the paper tube with piling-up of the paper fibers along each rib but without substantial cutting or otherwise weakening of the paper.

2. In combination, a paper tube and metal end cap attached thereto for rotative support of the tube, said attachment being so firm that the maximum stresses ordinarily encountered in commercial use and which often cause break down of the connection between the tube and end cap, will not cause such breakdown in this structure, said cap comprising inner and outer sleeves integrally connected in spaced relationship so as to provide an annular space closed at one end, and the end portion of the paper tube being tightly compressed into said annular space, a plurality of longitudinal, blunt, spaced, ribs formed on the external surface of said inner sleeve and extending substantially the full length thereof including the portion positioned opposite the inner surface of said outer sleeve, so that the annular space is divided up into a plurality of similar areas that distribute turning stresses uniformly between the cap and paper tube, and said ribs forming narrow longitudinal areas of restricted thickness in the annular space between the ribs and opposing areas of the outer sleeve so that the end portion of the paper tube that is wedged into this annular space is gripped by said longitudinal ribs which are embedded in the inner surface of the paper tube and form torque-resisting indentations in the wall of the tube but without cutting of the paper or otherwise weakenin the strength of the paper fibers, said ribs being held in said indentations and in positive engagement with the paper core by the opposing walls of the inner and outer sleeves which maintain the end portion of the paper tube in tightly compressed position and prevent the paper tube from expanding.

JOSEPH E. A. BLANCHET. 

